Hydrocarbon mineral oil



' July 25, 1933.A

C.VJ. RODMAN ET AL HYDRocARBoN MINERAL oIL Filed April 5o, 1929- 2 sheets-sheet 1 INVENTORS July 25,v 19337.V c J. RoDMAN Er AL HYDROCARBON MINERAL OIL Filed April 3o. 1929v ,2 Sheets-Sheet 2 Pat-cnt ejdeluly V- 1 UNITED STATES, PATENT' oFFflicE emanuela: J. novum AND vrurssaLL r. n UNnI'nE, or ALLLANcE, omo, AssIGNons To. THE BUcxnYnrw'rsm :DRILL contraint, or ALLInNcn, omo, .n conromirron or- OHIO maocannon MINERAL oIL r Application led April 30; 1929. Serial ANo. 359,30L` t rlhisl invention relates to'mineral hydro' carbon oils, particularly oil of the type adapted for use as an insulating and cool ingA medium in electrical apparatus," 'Oil 5 produced -according to the process herein de scribed has a high dielectric strengthand also the unusual property of' increasing in dielectric strength upon standing incontact -with the atmosphere, eventhough the atmosphere contains considerable moisture. Our process is adapted for the purification of new oils, that is, voils which have not been used previously in electrical apparatus or to the reconditioning of oils which have been 35 used previously in velectrical apparatus, in order to render themanhydrous, free from dissolved gases, .moisture and. volatile hydrocarbons.

Mineral hydrocarbon oils are refined forand find a'wide application as an Vinsulating,"

medium in oil submerged electrical apparatus because of the dielectric strength characteristics of the oil. The oils are used both as a cooling andinsulating medium in' trans-y formers, voltage regulators and asan insulating medium in cable joints and the like. When hydrocarbon oils -are used for these purposes, they are subjected to oxidation reactions resulting from the combined action of'heat absorbed from thevelectrical apparatus, and the oxygen in the atmosphere which has already access to the oil. drocarbons are l,chemically altered byy such g oxidation reactions resulting in. the forma-rv tion of organic acids, volatile hydrocarbons,

soap and deposits termed sludge When hydrocarbon mineral oils are used in electrical apparatus such as circult breakers, the

' arcing action which takes place results 1n 40 decomposition of the complex hydrocarbons forming elemental carbon, hydrogen, carbon monoxide, carbon dioxide, methane, and hydrocarbon vapors, all 4of which reduce the dielectric strength of the insulating medi- '45 um. Concurrently with the decomposition,C

of a portion of the oil, water may be formed -\due to the combination-of hydrogen evolved the zone-of the arc withoxygen dissolved in the oil. These traces `of water may be in true solution in the oil and together with the apparatus suitable Complex hy-4 evolved carbon particles of colloidal size contribute tofth'e deteriorationof the insulat-` ing-Ivalue of the oil. eretofore it has been attempted .to remove Water and suspensions byngravity, by centrifugal force, and by filtering. These processes, however, have been only partially suc- A cessful because they failed to remove water N of true solution, volatile hydrocarbons and dissolved gases such' as oxygen.- A

In Vaccordance with 4the-present invention wespray the oil to bepurified into .a vacuum.

The oil introduced intothe vacuum chamber is preferably under apressure of from 50 to 100 pounds per Vsquare inch, and the vacu um withinA the vacuumv chamber 'is maintained at as -low a pressure. as is practicable. We prefer' to maintain the vacuum in the .vacuum 'chamberfat apre'ssure of less than one-half pound persquare inch. When the oil under pressure is introduced into the vacuum chamber it is subjected to va sudden after havingwater and gases-removed therefrom is pumpedthrough suitable filters and delivered to `a storage tank.'

In the accompanying. drawings which illustrate the present preferred embodiment of `for carrying out l our process,

pressure drop or shock which causes'the wa-- ter and gases to escape therefrom. The oil-r Figure 1 shows in a diagrammaticfmanner the arrangement of the purifying apparatus,

Figure. 2 is a vertical section of the vacuumtank,

baiies for collecting and deflectingthe liquid,

Figure 4 is an elevation of-the baie shown in' Fig. Y3, and

1 Figure 5 is a front elevation of the spray nozzle, showing the arrangement of spray openings, f i

Referring to the drawings, there is shown. avacuum tank 2 connected by a pipe 3 to a vacuum pump 4 which maintains the vacuum chamber under reduced pressure. The

tank2 has a nozzle 5 arranged in its'bottom` for spraying the oil which'is to be purified.' 'i

The oil is heated in a heater' 6. to about se. loof F., preferably to about 140 F. and is v 85 Figure 3 is `a plan view of one of the n leasesdissolved gases and water therefrom. The nozzle 5 1s formed with a series of concentric openings 9 which spray the oil upewardly in the vacuum tank in a series of concentric cones. The spray is guided in its travel upwardly through the vacuum tank by a conical baffle 10 having its apex 11 eX- tending downwardly and surrounding the nozzle. A series of conical baffles 14 are arranged in the tank above the baflie 10. These baffles are shown in detail in Figs. 3 and 4. They areformed from a circular piece of metal which is slit to form segments 15. Each of these segments is then bent into a trough shape as indicated in Fig. 4. After the segments have been bentto form the troughs, the baiile consists of trough-like segments 15 separated by spaces 16. As shown, three of these conical b-aiiles are arranged one above the other in the vacuum tank. They are arranged so that the segments of the middle baille are in alinement with the spaces 16 between the segments of the upper and lower baflies. The oil sprayed from the nozzle 5 impinges upon the series of battles 14.

Due to the arrangement of the baflies as described, a tortuous path is formed between the segments of adjacent baffles. The oil impinges upon the segments of the baflles and drops down into and is collected by the segments of the next lower baflie. It flows in the downwardly and outwardly extending troughs and is collected by annular baliles 17 secured to the inside of the vacuum tank. Other bales 18 connected to the conical baffle 10 cooperate with the baiiies 17 to cause the oil to follow' the tortuous path indicated by the arrows in Fig. 2, after which it flows l to the bottom of the tank. The bottom 19 ofA the tank slopes downwardly so as to cause the oil to collect and be delivered to the pipe 20 by means of an exhaust pump 20.

As the oil sprayed from the nozzle 5 impinges against thebailles 14 and is collected thereby as above described, the gases and moisture removed therefrom the liquid by the vacuum flow out of the top of the tank through the pipe 3 and vacuum pump 4 and are exhausted through a pipe 21a.

The purified oil from which the moisture and gases have been removed flows from the vacuum tank through the pump 20 and pipe 20 to one of the filters 21. Theliters remove any suspended particles which may have been present in the liquid. In the drawings two filters 21 are shown and the system is provided with valves 22 so that one of the filters may be used While the other is being cleaned. The filtered oil flows through a pipe 23 to a storage tank 24.

We have found that by raising the pressure of the oil before it enters the vacuum tank, and then introducing it into the tank which is maintained at a very low pressure, we accomplish the removal of water-aud gases 'more eiiciently than if it were introduced into the vacuum under atmospheric pressure. We find that the sudden drop in pressure gives a jarring or cracking action which causes the water and dissolved gases to be expelled therefrom. The apparatus hereinabove described causes the oil sprayed from the nozzle 5, after having impinged against the conical baflies 14, to follow a tortuous path before it leaves the vacuum tank. 'ln this manner the liquid is subjected to tlie action of the vacuum for a relatively long time, so that the dissolved gases and water have anopportunity to escape from the oil. The apparatus causes vthe efiicient removal of moisture and gases from oils so asto increase their dielectric properties. The'apparatus is of simple constructionV involving the use of no revolving parts. We have found that oil purified in accordance with our invention has certain desirable properties which are not present in oil produced by other methods. For example, we have found that oil treated in accordance with our process, after having been allowed to stand in contact with the atmosphere, has an increased insulating value or dielectric strength. It would ordinarily be expected that if oil were allowed to stand in contact with the atmosphere, particularly moist atmosphere, the dielectric strength of the oil would be decreased. .We have found further that an oil treated in the above described apparatus has a greater dielectric strength after having stood in contact withthe atmosphere, even if the atmosphere is moist, than it had when it was first delivered from the purifying apparatus. A sample of oil was tested soon after it had come from the apparatus. This sample was found to have a dielectric strength of 35 kilovolts measured at the standard one-tenth inch gap using parallel electrodes one inch in diameter. The oil was allowed to stand in contact with the atmosphere for about three weeks and a'second sample was tested under the same conditions. The second sample had a dielectric strength of considerably over 40 kilovolts.

The exact theory which causes oil purified 'in accordance with our invention to increase in dielectric .strength has not yet been definitely determined We believe, however, that it is due to the fact that in our purification process certain impurities in the oil which tend to absorb water from the atmosphere are substantially entirely removed from the oil. After oil has been so purified itwill not absorb moisture from the atmosphere so as tio/i3@ decrease in dielectric strength, but will, on

the contrary, actually increase in dielectric' strength upon exposure to the atmosphere.

The reason for the increase ininsulating value may be accounted for by the 'oil absorbing certain gases without, however, absorb ing moisture. A

Whether or not our theories are correct, we h ave found that -there is an actual increase in the insulating value of oil uried in accordance with our invention, a r the oil has been allowed to stand for 'some time, and we do not limit ourselves to the theories which we have advanced to account for the increase in insulating valueof the oil. l Wehave illustrated and described the present preferred embodiment of an apparatus suitable for carrying out our process. sWe

also have described in detail the manner of practicing the process and have advanced cer tain theories which we now believe account for certain unlocked for phenomena.- It is to be understood, however,'that the inventionv may be otherwise embodied or practiced within the scope of the following claims.

' We claim 1. Mineral hydrocarbon oil produced by heating the oil to a temperature of 90-160 F. and spraying Vit under superatmospheric. 30

pressure into a rariied atmosphere maintained under ahigh vacuum to release moisture-and gases'from the'oil, and separating the moisture and gases fromthe oil, the oil having the property of increasing in dielec.

tric strength upon exposure to moist atmosphere. I

2. 'Mineral' hydrocarbon oil produced b heating the oil to a temperature of 9C-160' and spraying `it under superatmospheric pressure into a rariedatmosphere -maintained under a high vacuum to release moisture and gases from the oil, and separating the moisture and gasesl from the oil, the oil having a dielectric strengthof more than 35 kilovolts when tested under standard conditions using a -116 inch gapand parallel electrodes 1 inch in diameter.

3. Mineral hydrocarbon 'oil produced by .heating the o'il to a temperature of S90-160 F.

'and spraying it under a pressure of 50-100. pounds persquare inch into a raried atmos' phere maintained underv a' high vacuum' toV yrelease moisture and gases from the oil, and I separatin the moisture and gases-from the oil, the o' having th'eproperty of increasing indielectric strength 'upon exposure to moist atmosphere. .Y

4. Mineral hydrocarbon oil Aproduced by heating the oil to a temperature of S90-,160 F. and raying it under a pressure of 50-100 poun s per square inch-into arariied atmosphere maintained under a high vacuum to release moisture andl gasesfrom the oil, and

separating the moisture and gases from the oil, the oil having a dielectric strength of more than '3 5 kilovolts when tested under standard conditions using electrodes 1 inch in diameter.

5. Mineral hydrocarbon oil produced by heating'the oil to aatemperature of 90160 F. and spraying it under a pressure-of50-100 pounds per squareinch into a'rarited atmos phere maintained under a pressure of less than 1/2 pound per square inch to release'mois- Vture and gases from the oil, and separating Ahaving a dielectric strength of more than 35 kilovoltswhen tested under standard conditions using a 116 inch gap and parallel electrodes 1 inch -in diameter.

7. Mineral hydrocarbon? oil produced by heating the oil .to 'a temperature below 120 F. and spraying it under superatmospheric -pressure into a.rariied atmosphere maintained under a high'vacuum to release moisture and gases from -the oil, and separatin the moisture and'gases from the oil, the oil having the property of increasing .in dielectric strength upon exposure, to molst atmoshere. Y P Y CLARENCE J. RODMAN.

' A RUSSELL P. DUNMIRE.

a 115 inch gap and parallel vuc CERTIFICATE OF CORRECTIN.v

Patent No. 1,919,669. l July 25, 1933.

CLARENCE J. RoDMAN, ET A L.

It is hereby vcertified that error appears -in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 52, strike out the words "the liquid"; page 3, lines 5 and 10, respectively, after "value" insert "or dielectric strength"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record ot' the 'casein the Patent Office.

Signed-and sealed this 29th day of August, A. D. 1933.

M. J. Moore.

f (Seal) Acting Commissioner of Patents. 

